The present invention relates to control valves used in railcars or other load carrying vehicles. Specifically, the invention relates to control valves that control the opening and closing of a hopper gate on the underside of a railcar or other load carrying vehicles.
Control valves are typically used within hydraulic or pneumatic systems to direct flow to actuators and to generally control the flow path of a control fluid to insure proper operation of the system. Such control valves may be used with a pneumatic system such as those used with coal carrying railcars. Briefly, coal carrying railcars include a hopper gate on the underside of the railcar that opens and closes to dump coal from the railcar when over a dump site. The hopper gate is opened and closed by a pneumatic cylinder that is controlled by the control valve. As the railcar approaches the dump site, an air system is pressurized to prepare for dumping. When the railcar arrives at the dump site, the control valve provides pressurized air to the cap side of a piston such that the piston pushes the hopper gate open to dump the coal. After the coal has been dumped, the control valve is actuated to the closed position and the piston is refracted such that the hopper gate is closed and locked.